Methylphenidate is the treatment of choice for children and adults diagnosed with attention deficit/hyperactivity disorder (ADHD), including its inattentive subtype (formerly known as attention deficit disorder or ADD). Certain derivatives of methylphenidate have also been proposed for the treatment of ADD (see U.S. Pat. No. 6,025,502) and for the treatment of other neurological disorders and conditions (see U.S. Pat. Nos. 5,859,249, 6,025,502 and 6,486,177 and PCT application WO 99/36403).
Methylphenidate is a mild central nervous stimulant and is also taught for treating apathy, fatigue, cognitive decline, and depression in cancer patients, AIDS patients and other seriously ill patients. See U.S. Pat. Nos. 5,908,850, 6,127,385, 6,395,752 and 6,486,177, Challman and Lipsky, Mayo Clin. Proc., 75:711-721 (2000) and Leonard et al., Hum. Psychopharmacol. Clin. Exp., 19:151-180 (2004).
It has been reported that methylphenidate is not carcinogenic, and that there is a less than expected rate of cancer, in rats and humans taking methylphenidate. See Dunnick and Hailey, Toxicology, 103:77-84 (1995), National Toxicology Program, Natl. Toxicol. Program Tech. Rep. Ser., 439:1-299 (1995), Dunnick et al., Cancer Lett., 102:77-83 (1996) and Teo et al., Mutat. Res., 537:67-79 (2003). However, there is some evidence that methylphenidate is carcinogenic in mice. Dunnick and Hailey, Toxicology, 103:77-84 (1995) and National Toxicology Program, Natl. Toxicol. Program Tech. Rep. Ser., 439:1-299 (1995). Further, some types of tumors have been reported to be decreased, while other types of tumors have been reported to be increased. See Dunnick and Hailey, Toxicology, 103:77-84 (1995), National Toxicology Program, Natl. Toxicol. Program Tech. Rep. Ser., 439:1-299 (1995) and Dunnick et al., Cancer Lett., 102:77-83 (1996).